18 research outputs found
Dilepton decays of baryon resonances
Dalitz decay of baryon resonances is studied and expressions for the decay
width are derived for resonances with arbitrary spin and parity. Contributions
of the various terms in the transition matrix element are compared and
relevance of spin-parity and the resonance mass is discussed. Explicite
algebraic expressions are cited for spin5/2 resonances. The results can be
used in models of dielectron production in elementary reactions and heavy ion
collisions.Comment: 16 pages, 4 figure
Calculations of K+, K- and phi Production in Near-Threshold Proton-Nucleus Collisions
K+, K- and \phi meson production in proton-nucleus (pA) collisions has been
calculated within a BUU transport model. It is shown that the nucleon-hyperon
strangeness transfer channel is essential. The role of three-body reactions has
been investigated within the medium. The targetmass dependence of
production is predicted to give important information on the in-medium
properties of all three mesons.Comment: Talk presented by H.W.B. at the Budapest 2004 workshop on 'Hot and
Dense Matter in Relativistic Heavy Ion Collisions', March 24-27, 2004,
Budapest, Hungar
Longitudinal Scaling of Elliptic Flow in Landau Hydrodynamics
This study presents generalization of the Landau hydrodynamic solution for
multiparticle production applied to non-central relativistic heavy ion
collisions. Obtained results shows longitudinal scaling of elliptic flow
as a function of rapidity shifted by beam rapidity () for different
energies ( GeV and 200 GeV) and for different systems
(Au-Au and Cu-Cu). It is argued, that the elliptic flow and its longitudinal
scaling is due to the initial transverse energy density distribution and
initial longitudinal thickness effect.Comment: 7 pages 1 figur
A versatile method for simulating pp -> ppe+e- and dp -> pne+e-p_spec reactions
We have developed a versatile software package for the simulation of
di-electron production in and collisions at SIS energies. Particular
attention has been paid to incorporate different descriptions of the Dalitz
decay via a common interface. In addition, suitable
parameterizations for the virtual bremsstrahlung process
based on one-boson exchange models have been implemented. Such simulation tools
with high flexibility of the framework are important for the interpretation of
the di-electron data taken with the HADES spectrometer and the design of
forthcoming experiments
Origin of the low-mass electron pair excess in light nucleus-nucleus collisions
We report measurements of electron pair production in elementary p+p and d+p
reactions at 1.25 GeV/u with the HADES spectrometer. For the first time, the
electron pairs were reconstructed for n+p reactions by detecting the proton
spectator from the deuteron breakup. We find that the yield of electron pairs
with invariant mass Me+e- > 0.15 GeV/c2 is about an order of magnitude larger
in n+p reactions as compared to p+p. A comparison to model calculations
demonstrates that the production mechanism is not sufficiently described yet.
The electron pair spectra measured in C+C reactions are compatible with a
superposition of elementary n+p and p+p collisions, leaving little room for
additional electron pair sources in such light collision systems.Comment: 11 pages, 2 figures, \usepackage{epsfig